We will, of course, have to start with an explanation of the passive voice in English. Both English and Spanish have two voices: active and passive. Active is when the subject is acting: John hit the ball. Passive is when the subject is being acted upon: John was hit by the ball. In the latter, the subject isn’t doing anything; something is happening to him.
Your English teachers have told you to avoid using passive voice. It’s weak, if it’s avoidable. For example, don’t say, The cake was eaten by the children. Say, The children ate the cake. But if you want to say, Your cake was popular; every last crumb was eaten. that’s actually OK, because the subject isn’t important. Who ate every last crumb? How would you reword that to be active voice? “The people ate every last crumb”? That’s really not what you want to emphasize here.
At any rate, the purpose here is for you to learn how to form the passive voice in Spanish. It’s actually very easy. You use “ser” and the past participle: La torta fue comida. – The cake was eaten. The books were written. – Los libros fueron escritos. Note that the past participle MUST agree in number and gender with the subject. Also remember that the past participle CAN’T change if you use a form of “haber” with it: La torta fue comida. María ha comido la torta.
Click here to go to the Power Point on past participles if you need a review. Another important note: although it’s usually in the preterit, the passive voice can be in any tense: La torta será comida. The cake will be eaten. La torta ha sido comida. The cake has been eaten. La torta es comida. The cake is eaten.
Click here to go to a review of the past participle (along with the present perfect tense).
Now, don’t let the way the homework is set up fool you. Make this sentence passive voice: Juan abrió la puerta. La puerta fue abierta (por Juan). You go from John opened the door. to The door was opened (by John). That’s not hard, when you understand what you’re doing. The homework sentences are not actually the greatest sentences, because if you can say who did the action, you really shouldn’t use the passive voice. But the exercise is just to get you to practice forming the passive voiced.